Early transition metal catalysts for olefin polymers by coordination polymerization are well-known, typically those are the traditional Ziegler-type catalysts based on Group 4 and 5 of the Periodic Table (IUPAC new notation) and the newer metallocene catalysts based on Group 4-6 metals. However specific late transition metal catalysts suitable for olefin polymerization had not offered the same levels of activity or molecular weight capability for olefin polymerization during the development of these catalyst systems and additional work was published addressing this lack,
In Johnson, Killian, and Brookhart, J Am. Chem. Soc., 1995, 117, 6414 the reporters describe the use of Ni and Pd complexes for the solution homopolymerization of ethylene, propylene, and 1-hexene. The catalyst precursors are square-planar, M.sup.2+, d.sup.8, 16 electron complexes incorporating substituted, bidentate diimine ligands. The active coordination sites are occupied by either methyl or bromide ligands. Methyl ligand complexes were activated with H.sup.+ (OEt.sub.2).sub.2 [B(3,5-(CF.sub.3).sub.2 C.sub.6 H.sub.3).sub.4 ].sup.- and bromide ligand complexes were activated with methylalumoxane (MAO) or diethylaluminumchloride as cocatalysts.
European patent publication EP-A2-0 454 231 describes Group VIIIb metal catalysts said to be suitable for the polymerization of ethylene, a-olefins, diolefins, functionalized olefins, and alkynes. The described catalyst precursors are Group VIIIb metal (Groups 8, 9, 10, IUPAC new nomenclature) compounds which are subsequently activated by compounds including discrete borate anions. Ethylene homopolymerization in solutions of methylene chloride, toluene and diethyl ether are illustrated.
Since the new late transition metal catalysts exhibit characteristics different from those of transition metal metallocene catalysts or traditional Ziegler-Natta catalysts when used in olefin polymerization, the effects of mixing those catalysts for determining useful benefits are of great interest.